1. Field of the Invention
The inventive concept relates to a pressure conductive sheet, and more particularly, to a pressure conductive sheet for substantially preventing interference between signal terminals and thus improving an electrical characteristic by extending a ground area between connection terminals.
2. Description of the Related Art
Semiconductor products are necessary elements to perform various functions in a wide variety of technological fields.
Even though recent semiconductor products may be capable of performing more functions than older semiconductor products, the size of more recent semiconductor products may still be smaller than previous products so they may be used in microminiaturized and highly-integrated devices and products.
Some semiconductor products are package types that are configured to be mounted on a circuit substrate. Multiple semiconductor products may be mounted two-dimensionally on one circuit substrate.
On the other hand, recent stacking-type, or stacked, semiconductor packages may be mounted on a circuit substrate by stacking one semiconductor package on top of another. This arrangement allows devices to be further miniaturized.
Stacked semiconductor packages generally use a package-on-package (PoP) type of coupling a package to stack one semiconductor device upon another via soldering.
However, using a solder joint requires a high temperature of 240° or more and this may cause the package to bend or may create a short-circuit between soldering faces due to a severe thermal stress.
To prevent these problems caused by soldering, semiconductor chips may be stacked within one package. However, stacking multiple semiconductor chips within one package may cause problems with package yield, manufacturing costs, etc.
Alternatively, a package stack using a pressure conductive rubber (PCR) may be used. Pressure conductive rubber is made up of conductive particles that contact each other when pressure is applied to the rubber. Thus, if pressure is applied to one point of a sheet of PCR by a connection lead, for example, the portion of the PCR compressed by the connection lead becomes conductive and the portions of the PCR that are not being compressed by the connection lead would not be conductive. Instead, they may serve as insulation.
A plurality of semiconductor packages may be stacked by using PCR so that the connection bumps of the semiconductor packages compress the PCR, generating electrical connections with other semiconductor devices or with a connector body, for example. A connector body may be made of solidified insulation powder.
However, although stacking semiconductor devices with PCR should yield similar results to stacking semiconductor devices using solder, when the two methods are compared, the PCR structure provides a lowered-signal integrity at a specific frequency.
Therefore, a matching circuit must be used at an inductive interconnection section in the stacked circuit to improve a signal integrity when using a PCR structure, or a similar structure that requires that pressure be applied to the semiconductor device connections.